तथामुष्मिल्लोके लोक इति स य एतमेव विद्वानुपास्ते परोवरीय एव हास्या स्मिँल्लोके जीवन भवति तथामुष्मिल्लोके लोक इति लोके लोक इति ॥ ४ ॥
In plain words
And as for the saying, 'In that world, a world': whoever meditates upon [the Udgītha] knowing it thus, his life in this world indeed becomes superior, and in the next world he gains a corresponding world — yes, a world.
Close to the Sanskrit
And 'in that world a world', so he who knowing this very [Udgītha] meditates, superior indeed becomes his life in this world and in that world a world, in the world a world.